This invention relates to an armature coil conductor to be connected to a commutator segment by ultrasonic welding for use in a direct-current motor, and a method of manufacture therefor.
FIG. 11 is a partial cross section showing an armature 10 employing conventional armature coil conductors. Conventionally, the end plates 2 and the laminated core (armature core) 3 are fastened by press fitting to the shaft 1. The U-shaped armature coil conductors 6 pass through the end plate 2 and laminated core 3, which have a plurality of slots 3a parallel to their circumference, as shown in FIG. 12. Also, a commutator consisting comprising segments 8 and a mold 4 fastening the commutator segments 8 are arranged parallel to the circumference of the shaft 1 and fastened thereto by press fitting.
As shown in FIG. 13, the conventional armature coil conductor 6 has a circular cross section and consists of a conductor which has a circular cross section, is covered with an insulation coating and is formed in the shape of a U, and the insulation coating of the lead portions 6a at each end of the conductor only are removed by cutting, etc.
FIGS. 14 to 18 show the conventional method for manufacturing an armature employing the armature coil conductors.
First, end plates 2 and a laminated core 3 are fastened to a shaft 1 by press fitting as shown in FIG. 14. Armature coil conductors 6 are prepared to match the number of slots 3a, and are inserted into the slots 3a after or at the same time that insulating paper 5 is inserted, as shown in FIG. 15, which is a view from X in FIG. 14.
Next, the armature coil conductors 6 are arranged in pairs and formed so that they overlap above the commutator segments 8 such that the lead portions 6a at the ends of the armature coil conductors 6 have their upper leads 6c on the outside and their lower leads 6d on the inside radially parallel to the armature as shown in FIG. 16.
As shown in FIG. 17, the lead portions 6a at the ends of the armature coil conductors 6 are welded to the commutator segments 8 using an ultrasonic welder 11. FIG. 18 is a cross section along line 18--18 in FIG. 17. As shown in FIG. 18, the end portion 7a of the horn 7 of the ultrasonic welder 11 has two protrusions 7c. Together these protrusions 7c function as a welding jig during ultrasonic welding to ensure that the lead portions 6a of the armature coil conductors 6 are welded securely to the prescribed position on the commutator segments 8, and a U-shaped groove 7b is formed between the protrusions 7c. The paired lead portions 6a of the armature coil conductors 6 fit into this U-shaped groove 7b. As shown in FIG. 17, pressure is applied to the horn 7 parallel to the arrow P so that the lead portions 6a are pressed against the commutator segment 8, and by vibrating the horn 7 parallel to the arrows F along the axis of the armature, the lead portion 6a of the upper lead 6c is welded to the lead portion 6a of the lower lead 6d, and the lead portion 6a of the lower lead 6d is welded to the commutator segment 8, connecting each electrically and forming an armature coil.
However, if the number of slots 3a in the armature is increased, or if the diameter of the armature coil conductors is enlarged to increase the cross-sectional area of the armature coil conductors 6, the lead portion spacing 9 between the lead portions 6a of adjacent armature coil conductors 6 will become narrow, as shown in FIG. 18. For that reason, it becomes necessary to make the protrusions 7c of the horn 7 thinner and reduce the protrusion with 7d of the protrusions 7c, since they must be inserted into this lead portion spacing 9 during ultrasonic welding. As the protrusions 7c become thinner, they become weaker and are unable to withstand the vibrations which arise in the horn 7 itself during ultrasonic welding, and there is a risk that the protrusions 7c will break.